Pressure sensor having gauge resistors and temperature compensating resistors on the same surface

Abstract

A pressure detector comprises a pressure sensitive element composed of a semiconductor substrate having at least four gauge resistances and outputting signal in response to a pressure. A pressure transmission member is provided on the surface having the gauge resistors of the pressure sensitive element, for transmitting the pressure to the pressure sensitive element. Taking a crystal face of (110) as the face orientation of the pressure sensitive element, a bridge circuit is constructed by disposing a pair of gauge resistors in the direction of <110> of the crystal axis, disposing another pair of gauge resistors in the direction of <100> of the crystal axis and by connecting them each other. The bridge circuit is located within a pressurized surface which the pressure transmission member presses. Further, temperature compensating resistors are disposed in the direction of <100> of the crystal axis so as to be located also within the area of the pressurized surface.

What is claimed is: 
     
       1. A pressure detector, comprising: substrate means;   gauge resistor means formed on said substrate and whose resistance values change in response to a compression stress applied thereon;   temperature compensating resistor means formed on said substrate means for compensating a temperature of said gauge resistor means; and   pressure transmission member means, bonded on said substrate means so that said gauge resistor means and said temperature compensating resistor means are located entirely within a bonded surface, for transmitting a pressure to be detected to said gauge resistor means as said compression stress.   
     
     
       2. The pressure detector according to claim 1, wherein each of said resistor means is within the bonded surface of said pressure transmission member means and is formed approximately at a radial center portion of said substrate means. 
     
     
       3. The pressure detector according to claim 1, wherein each of said resistor means has a line width and a line length which are in a range within the bonded surface of said pressure transmission member means. 
     
     
       4. The pressure detector according to claim 1, wherein said substrate means is made of a semiconductor whose face orientation is (110), a bridge circuit is formed by disposing a pair of resistors of said gauge resistor means in the direction of <110> of the crystal axis and by disposing another pair of resistors of said gauge resistor means in the direction of <100> of the crystal axis, and said temperature compensating resistor means are disposed in the direction of <100> of the crystal axis. 
     
     
       5. The pressure detector according to claim 4, wherein said pressure transmission member means includes: a cup having a thin diaphragm portion movable with variations in said pressure; and   a rod having one end connected to said diaphragm portion and another end connected to said substrate means.   
     
     
       6. The pressure detector according to claim 1, wherein a buffer layer for relaxing a concentration of stress at the bonded surface of said pressure transmission member is provided between said pressure transmission member and said substrate means. 
     
     
       7. The pressure detector according to claim 1, wherein said pressure transmission member means includes a rod. 
     
     
       8. The pressure detector according to claim 7, where said pressure transmission member means further includes a cup having a thin diaphragm portion movable within variations in said pressure, and said rod has one end connected to said diaphragm portion and another end connected to said substrate means. 
     
     
       9. A pressure detector, comprising: substrate means having gauge resistors on a main surface thereof for outputting signals on the basis of changes of resistance values of said gauge resistors;   a pressure transmission member, disposed on the main surface of said substrate means, for transmitting a pressure to said gauge resistors;   an electrically conductive base means for disposing and fixing said substrate means thereon; and   a signal transmission medium, sealed hermetically to said base means, for producing/receiving signals between said substrate means and an outside;   wherein said signal transmission medium is formed to transmit gauge output from said gauge resistors, an insulating film is formed on a back of said substrate means between said base means and said substrate means said substrate means is grounded, an electrically conductive sealing member is provided on said gauge resistors on said substrate means between said pressure transmission medium and said substrate means through an intermediary of an insulating film, said sealing member is grounded, and a buffer layer for relaxing a concentration of stress at the bonded surface of said pressure transmission member is provided between said pressure transmission member and said sealing member.   
     
     
       10. The pressure detector according to claim 9, wherein said substrate means, on the back of which said insulating film is formed, is fixed to said base means by an adhesive and said adhesive crawls up to the side of said substrate means at the lower end surface of said substrate means (FIG. 5). 
     
     
       11. The pressure detector according to claim 9, wherein said buffer layer is made of a film-like member. 
     
     
       12. The pressure detector according to claim 9, wherein said buffer layer is made from an adhesive containing fillers. 
     
     
       13. A pressure detector, comprising: a substrate formed with piezoresistive elements thereon for producing a signal corresponding to a compressive stress applied thereto;   a first insulating film formed on said substrate to cover said piezoresistive elements;   an electrically conductive seal film formed on said first insulating film and electrically connected to a fixed electrical potential;   a second insulating film formed on said seal film;   a buffer means provided on said second insulating film; and   a rod disposed on said buffer layer and which entirely covers said piezoresistive elements, said rod transmitting a pressure to be detected onto said piezoresistive elements as said compressive force through said layer and films.   
     
     
       14. The pressure detector according to claim 13, wherein said buffer means has a thickness sufficient to prevent electrical conduction between said rod and said piezoresistive elements.